The invention relates to a surgical instrument for applying a bone plate fixing device comprising a first bone contacting element with a rod-shaped connecting member projecting therefrom and defining a longitudinal direction, and a second bone contacting element displaceable on the connecting member in a direction towards the first bone contacting element, with a first tool element positionable in a contacting position on the second bone contacting element, and a second tool element removable from the first tool element, with a transportation device for stepwise transportation of the connecting member with the second tool element in several transportation steps in a proximal direction away from the first tool element resting in the contacting position on the second bone contacting element.
An instrument of the kind described at the outset is known, for example, from DE 197 00 474 C2. With a second tool element formed by two clamping jaws the rod-shaped connecting member can be clamped in a clamp position and moved in the clamp position relative to the second bone contacting element.
A subsequent grasping of the connecting member with the clamping jaws is possible in the above-described manner.
With the known instrument, however, a defined transportation of the connecting member relative to the second bone contacting element is not clearly ensured. Moreover, it is difficult to securely grasp a smooth connecting member. With structured connecting members there is the problem that a structure of the connecting member may dig into the clamping jaws and cause damage to these. In any case, when high pulling forces act on the second tool element there is the danger that the clamping jaws will slide off the connecting member. Furthermore, the instrument is difficult to clean when the clamping jaws have been damaged by sharp-edged structures of the connecting members.
The object underlying the present invention is therefore to so improve a surgical instrument of the kind described at the outset that the bone contacting elements of the fixing device can be displaced relative to each other in a simple way and the handling of the instrument is simplified.